Pharmaceutical preparations intended for injection are usually supplied as prepared injection solutions for immediate use. In many cases, such pharmaceutical preparations consist of proteins, the solutions of which cannot be heat sterilised. For this reason, effective preservatives are generally added to the solutions, which in turn means that the preservative is also injected into the patients. If this preservative could be removed, the patient would be spared toxic exposure, which must be considered particularly serious when the pharmaceutical preparation is used constantly. One example in this respect is diabetics injecting insulin, and the prevalent product on the market contains phenol as preservative. Another example is somatropin, where two dominating manufacturers use m-cresol as preservative and a third uses benzyl alcohol. It is also common for manufacturers of this type of drugs to supply special disposable syringes with dose indicator.
Especially for the last-mentioned reason, i.e. that the drugs are supplied in special disposable syringes, more or less complicated methods for removing the preservative cannot be applied. The present invention offers on the other hand a very simple but at the same time very effective method for removing preservatives from such solutions, the method being so simple that it can even be applied in connection with disposable syringes of the type involved. According to the present invention, it has thus been found that hydrophobic zeolites can be used for this purpose in a very simple, quick and effective manner. The fact that the invention is at the same time surprising is illustrated by the following.
The use of zeolites for adsorption of some specific types of organic compounds is per se known. Thus, e.g. U.S. Pat. No. 5,108,617 discloses the use of hydrophobic zeolites for adsorption of detergents from a solution containing the same, while PCT Application SE93/00582 discloses the use of hydrophobic zeolites for adsorption of hydrophobic proteins or peptides. However, none of these publications indicates that such hydrophobic zeolites could be usable for efficient removing of the type of compounds that is intended according to the present invention, viz. preservatives from (poly)peptide solutions, for instance solutions of pharmaceutical products. Moreover it is particularly surprising that the invention has been found to function extremely well for purifying solutions containing peptides or proteins, since, as mentioned above, hydrophobic zeolites have been used precisely to adsorb peptides or proteins.